Each year approximately 3.5 million cubic metres of silt must be removed from Harwich Harbour and the estuary to ensure clear access to the ports of Felixstowe, Harwich, Ipswich and Mistley.
The build-up continues relentlessly – the North Sea contains a high level of mud in suspension, and approximately 5,000 cubic metres of this mud settles in the harbour every day.
We carry out maintenance dredging approximately every ten weeks to keep the deepwater channel at 14.5 metres below chart datum. This means that the channel is always guaranteed to be a minimum depth of 14.5 metres depth. The tide can add as much as 4 metres more, giving 18.5 metres depth at high water.
Dredging work in Harwich Harbour is currently contracted to a joint venture of Van Oord and Boskalis, which is part-way through a three-year contract. To ensure the most competitive operation, our dredging contract is subject to a Europe-wide tender process every three years, with the possibility of an extension.
The Van Oord and Boskalis operation uses trailer suction hopper dredgers (TSHD), with each dredge lasting between ten days and a fortnight. The material removed is disposed of at an authorised dispersive site.